The present invention is directed to reflective pavement marker without a housing or exterior shell. The reflective members are encapsulated in the housingless body itself This invention also relate to durable abrasion resistant reflective pavement markers. The primary use of this type of pavement marker is for roadway delineation. Pavement markers are commonly agglutinated to the roadway centerline, edgeline or as lane dividers and to serve as perimeter.
Reflective pavement markers generally made using a housing, which is some time referred to as a shell, this housing made of either acrylic, polycarbonate, ABS or other suitable thermoplastics materials. The housing act as a casing to enclose the resinous filler material that, after curing form the structural body of the pavement marker. The reflective member commonly placed either on one side or two opposite sides of the pavement marker facing on coming traffic, generally made as integral part of the housing or agglutinated to the housing then sealed with a metalized coating prior to being filled with the structural resinous body. Reflective members give nighttime visibility of the marker by reflecting headlights of the oncoming traffic.
A marker with a housing not only an added expense to the over all cost of such a product but also tend to chip away from the resinous body due to the severity of traffic impact and the difference in the coefficient of thermal expansions of the two materials, the housing and the resinous body. Additionally, sealing the cube-corner reflectors with a metallic sealer reduces reflectivity considerably.
Previously, attempts have been made to develop a housingless pavement markers. Pavement markers such as U.S. Pat. No. 4,498,733 to Flanagan, U.S. Pat. No. 4,875,798 to May and U.S. Pat. No. 4,208,090 to Heenan use an improved reflective members by using peripheral walls to provide supports and recesses at the bottom of the marker body that form hollowed base. However, unlike this invention, the reflective members are not protected by raised ridges on the outside surface that also help prevent buckling and lift-off the diamond like film coating for abrasion resistance without the need for prior coating of said surface with a polymeric materials. Other deficiency of markers such as 733 is that unless filling the hollowed base of the marker with a sealer material, there is considerable reduction in the adhesion parameter of the marker's base, thereby failure and dislodgement occur due to flexural stresses. The wetting parameter for adhesion of the present marker base to roadway can further be enhanced by spraying coarse sand on the planar base area of the marker body prior to the solidification o f the cast resinous body, as previously proven to be effective, as in U.S. Pat. No. 3,332,327 to Heenan, which is referenced herein. Thus, a need exist for an inexpensive yet have high structural strength and functional reflective marker that solve the problem of housing, having durable reflective members due to very high abrasion resistance diamond like carbon film coating, daytime and night time visibility and full planar base without recesses for durable agglutination to the roadway.